A confocal fluorescence imaging system, including a laser-based scanner attached to an epifluorescence microscope, control computer with 80386 processor for efficient image analysis, dual detector channels, motorized focus control, transmitted light detector, photo record system, Micro SEMPER software package, and an external image archiving storage component is requested. The use of the instrument is to be shared among researchers in several departments at Roswell Park Memorial Institute. The projects requiring this equipment include, but are not limited to, studies of the cytoskeleton and organelles in mammary epithelial cells; localization of oncogene proteins; lymphocyte membranes, receptors and cytoskeleton; molecular organization and fusion of membranes; effects of drugs on normal and tumor cell growth and differentiation; tumor cell heterogeneity; subcellular abnormalities in mutant mice; tumor cell structure, function, and growth, drug resistance in human tumors; and localization of specific proteins in mouse embryos.